Zone I Rupture of the Flexor Digitorum Profundus Tendon Caused by Blunt Trauma: A Case Report

Zone I Rupture of the Flexor Digitorum Profundus Tendon Caused by Blunt Trauma: A Case Report

Zone I Rupture of the Flexor Digitorum Profundus Tendon Caused by Blunt Trauma: A Case Report Eric P. Hofmeister, MD, Charles E. Craven Jr., MD Trauma...

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Zone I Rupture of the Flexor Digitorum Profundus Tendon Caused by Blunt Trauma: A Case Report Eric P. Hofmeister, MD, Charles E. Craven Jr., MD Traumatic ruptures of flexor tendons as a result of blunt trauma without an associated pathologic condition are rare. This is a case of a midsubstance flexor tendon rupture as a result of closed direct trauma. The patient sustained a flexor digitorum profundus (FDP) rupture 1 cm proximal to its insertion on his right ring finger without any accompanying laceration. Additionally, this case highlights the utility of ultrasound in diagnosing ruptured flexor tendon, which has been demonstrated in prior studies. (J Hand Surg 2008;33A:247–249. Copyright © 2008 by the American Society for Surgery of the Hand.) Key words Blunt trauma, flexor tendon rupture, ultrasound, flexor digitorum profundus.

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HE MAJORITY OF FLEXOR TENDON ruptures reported are avulsions that occur at the tendon insertion and are the result of a hyperextension mechanism against resistance.1–3 Additional sites of rupture include the mid-digit level, palm, carpal tunnel, wrist, and musculotendinous junction.2,3 When a rupture occurs at any of these locations, there is a pathological condition associated with the tendon rupture, such as rheumatoid arthritic changes in the bone, pyogenic infections, gout, syphilis, tuberculosis, gonorrhea, rough volar surfaces of the carpal bones, hook of the hamate nonunions, repetitive motion, prominent implants, or degeneration of tendon substance associated with age.4 –14 In this case, we report a patient who sustained an FDP rupture 1 cm proximal to its insertion on his right ring finger as a result of a single, closed, traumatic impact to his digit with no accompanying laceration or predisposing pathologic condition. Ultrasound of the flexor sheath was used and assisted in diagnosing the ruptured flexor tendon.

From the Department of Orthopedics, Naval Medical Center San Diego, CA; Department of Orthopedics, Naval Hospital, Okinawa, Japan. Received for publication December 10, 2004; accepted in revised form September 18, 2007. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Eric P. Hofmeister, MD, Naval Medical Center, San Diego, Department of Orthopedics, 34800 Bob Wilson Dr., Suite 112, San Diego, CA 92134 –1112; e-mail: [email protected]. 0363-5023/08/33A02-0016$34.00/0 doi:10.1016/j.jhsa.2007.09.018

FIGURE 1: Radiographs demonstrating healing fractures of the patient’s middle, ring, and small fingers.

Ultrasound has been reported to be of value in preoperative evaluation of the status of the flexor tendon and the location of the proximal stump.4,15 CASE REPORT A 38-year-old, right-handed man presented to orthopedics 9 days after sustaining a closed, blunt injury involving a 500-pound vent fan motor falling directly onto his right hand. The patient was initially evaluated and splinted by his primary medical doctor. Upon referral to an orthopedic surgeon, the initial physical exam and radiographs revealed transverse, minimally displaced fractures of the patient’s middle phalanx of the long finger, middle phalanx of the ring finger, and distal phalanx of the small finger (Fig. 1). The patient was neurovascularly intact. Specifically, the patient demonstrated the ability to flex the distal interphalangeal (DIP) joints of his long and small

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FIGURE 2: A The ultrasound demonstrates a smooth, homogenous FDP tendon proximal to patient’s zone of injury (solid arrow) and B heterogeneous substrate of scarred tendon (small x’s) overlying fracture site (thin arrow).

fingers. However, it was noted that the patient did not flex the DIP joint of his right ring finger, which was thought to be secondary to pain. He was placed into a short arm cast with volar outriggers for 4 weeks and subsequently placed in a dorsal block extension splint for an additional 3 weeks while beginning gentle passive range of motion. Upon presentation to our facility at approximately 10 weeks after injury, the patient still could not flex the distal phalanx of his ring finger and was bothered by his digit that could be passively hyperextended. Radiographs showed good callus formation of his fractures. To aid with diagnosis and planning, a real-time ultrasound of the patient’s right ring finger was performed to determine whether the tendon was ruptured or simply entrapped in scar tissue. The study demonstrated a normal, homogeneous tendon proximal and distal to the fracture site (Fig. 2A) and a heterogeneous mass at the level of the fracture site, consistent with a ruptured FDP tendon (Fig. 2B). Also, the ultrasound was able to demonstrate a normal-appearing FDP tendon proximal and distal to the fracture site. There was good real-time motion of the distal FDP tendon with passive motion of the DIP joint, but no FDP motion at the fracture site. After a complete discussion of surgical options, the patient desired a single, definitive procedure to allow an expeditious return to his full work duties; he did not desire the use of silicone rods, implants, or prolonged therapy. The patient had surgical exploration of the ring finger flexor tendon via a volar Bruner incision, and the middle phalanx fracture was well healed without any volar spikes or fragments. The FDP tendon was found to be completely disrupted at the level of the fracture site, with the distal stump scarred and adherent within the A-4 pulley. After the proximal stump was located and freed, it was still retracted approximately 12 mm, making direct repair impossible (Fig. 3). An FDP tenodesis of the distal stump to the middle phalanx was performed using a microsuture anchor (Mitek, Norwood, MA) and 2 K-wires (size 0.9 mm [0.035 in.]) placed across the DIP joint to protect the repair. The K-wires were removed 6 weeks after the index procedure. By 3 months, the patient had regained nearly full range of motion of the metacarpophalangeal (0°–95°) and

FIGURE 3: Intraoperative photograph demonstrating approximately 12-mm gap of FDP tendon, making primary repair of the tendon impossible.

PIP (0°–90°) joints, had no hyperextension deformity of the DIP joint, and was pain free. At the 9-month follow-up examination, he continued to perform the duties demanded of him by the military and has remained on full, unrestricted active duty. DISCUSSION Ruptures of the flexor tendons due to closed direct trauma are rare, with the exception of avulsion-type injuries, which often occur from sporting activities. Commonly known as jersey fingers, these injuries involve an avulsion of the FDP tendon from its insertion on the distal phalanx. Folmar et al2 presented a series of 12 cases of closed flexor tendon rupture in 10 patients; all of these are accounted for by 1 of 3 mechanisms: forceful hyperextension, flexion against resistance, and atraumatic rupture attributable to a secondary pathologic condition in the hand. Similar mechanisms of avulsions have also been reported by others.1,16,17 Few authors have reported on traumatic flexor tendon rupture in the digit and palm, and in all cases the patient had a predisposing condition and all occurred at or proximal to the lumbrical origin.5,18,19 In the first case,5 an isolated FDP rupture occurred secondary to a forceful flexion of the digit. The site of rupture was not diagnosed before surgery,

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and in fact, the digit was explored at the distal insertion site prior to a second incision in the palm, where identification and repair of the tendon was repaired.5 In a second case report by Takami et al,18 a patient sustained a closed tendon rupture secondary to repetitive trauma to the palm from a Japanese fencing stick. Walker et al19 described a FDP rupture proximal to the origin of the lumbrical after the patient lifted a steel ramp. Again, at the time of operation, the distal digit was first explored, and only after further palmar exploration was the site of rupture identified. Finally, in a series of 10 patients with flexor tendon ruptures, 9 had manual jobs requiring repetitive motion, and all ruptures occurred while the hand was engaged in resisted flexion.20 The use of ultrasound as a diagnostic modality for flexor tendon rupture has been previously cited in the literature. Wang et al15 present a series of 8 patients, all of whom presented with an inability to flex their affected digit. In their series, ultrasound correctly identified 3 complete FDP ruptures, which were verified intraoperatively. Ultrasound also was used to confirm that 5 patients had intact flexor tendons. Three of these patients went to surgery for various reasons related to their flexor tendons (tenolysis, scar release, arthrodesis) and were confirmed to have intact flexor tendons intraoperatively. Lee et al4 published similarly positive results regarding the use of ultrasound as a diagnostic modality in flexor tendon pathology. They used ultrasound to evaluate 20 potentially injured flexor tendons in 13 digits of 10 patients. The mean time between injury and ultrasound was 22 days. Ultrasound correctly identified the status of the flexor tendon in 18 of 20 cases. Additionally, in completely lacerated tendons, the location of the proximal stump was correctly determined in 5 of 6 digits. In partially lacerated tendons, ultrasound was accurate in 1 of 2 cases in this series. The case presented here is unique in 2 regards. First, there was no pathologic condition predisposing to flexor tendon rupture. Second, the patient’s tendon disruption was caused by a single blunt trauma and not the usual reported pathological mechanisms of repetitive trauma or avulsion injury. Although it is operator dependent, preoperative ultrasound was useful in confirming the diagnosis, ruling out an adhesion, and aiding in patient counseling. Ultimately, the patient was very satisfied with his surgical result and has been able to continue in all his activities and work. REFERENCES 1.Murphy BA, Mass DP. Zone I flexor tendon injuries. Hand Clin 2005;21:167–171. 2.Folmar RC, Nelson CL, Phalen GS. Ruptures of the flexor tendons in hands of non-rheumatoid patients. J Bone Joint Surg 1972;54A:579 –584. 3.Boyes JH, Wilson JN, Smith JW. Flexor-tendon ruptures in the forearm and hand. J Bone Joint Surg 1960;42A:637– 646. 4.Lee DH, Robbin ML, Galliott R, Graveman VA.

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Ultrasound evaluation of flexor tendon lacerations. J Hand Surg 2000;25A:236 –241. 5.Kumar S, James R. Closed rupture of flexor profundus tendon in the palm. J Hand Surg 1985;10B:193–194. 6.Hohendorff B, Kurzen P, Boss A. [Flexor tendon rupture after palmar osteosynthesis using a multidirectional fixedangle plate.]. Unfallchirurg 2006;109:995–997. 7.Koizumi M, Kanda T, Satoh S, Yoshizu T, Maki Y, Tsubokawa N. Attritional rupture of the flexor digitorum profundus tendon to the index finger caused by accessory carpal bone in the carpal tunnel: a case report. J Hand Surg 2005;30A:142–146. 8.Imai S, Kubo M, Kikuchi K, Ueba H, Matsusue Y. Spontaneous rupture of the flexor digitorum profundus and superficialis of the index finger and the flexor pollicis longus without labor-associated tendon loading. J Hand Surg 2004; 29A:587–590. 9.Cognet JM, Dujardin C, Popescu A, Gouzou S, Simon P. [Rupture of the flexor tendons on an anterior plate for distal radial fracture: four cases and a review of the literature]. Rev Chir Orthop Reparatrice Appar Mot 2005;91:476 – 481. 10.Hashizume H, Nishida K, Fujiwara K, Inoue H. Spontaneous “spaghetti” flexor tendon ruptures in the rheumatoid wrist. Mod Rheumatol 2004;14:257–259. 11.Kato N, Nemoto K, Arino H, Ichikawa T, Fujikawa K. Ruptures of flexor tendons at the wrist as a complication of fracture of the distal radius. Scand J Plast Reconstr Surg Hand Surg 2002;36:245–248. 12.McLain RF, Steyers CM. Tendon ruptures with scaphoid nonunion. A case report. Clin Orthop Relat Res 1990:117– 120. 13.Lillmars SA, Bush DC. Flexor tendon rupture associated with an anomalous muscle. J Hand Surg 1988;13A:115–119. 14.Rae PS, Finlayson D. Closed rupture of flexor pollicis longus tendon associated with treatment of Bennett’s fracture. J Hand Surg 1984;9B:129 –130. 15.Wang PT, Bonavita JA, DeLone FX Jr., McClellan RM, Witham RS. Ultrasonic assistance in the diagnosis of hand flexor tendon injuries. Ann Plast Surg 1999;42:403– 407. 16.Peterson JJ, Bancroft LW. Injuries of the fingers and thumb in the athlete. Clin Sports Med 2006;25:527–542, vii–viii. 17.Mansat M, Bonnevialle P. Traumatic avulsion of the flexor digitorum profundus tendon. Report of nineteen cases. Ann Chir Main 1985;4:185–196. 18.Takami H, Takahashi S, Ando M. Rupture of the flexor digitorum profundus tendon in the palm caused by repeated, chronic direct trauma. J Hand Surg 1993;18A:65– 67. 19.Walker LG, Lesavoy MA. Traumatic rupture of the profundus tendon proximal to the lumbrical origin. J Hand Surg 1990;15A:484 – 486. 20.Imbriglia JE, Goldstein SA. Intratendinous ruptures of the flexor digitorum profundus tendon of the small finger. J Hand Surg 1987;12A:985–991.

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